Pen needle assembly for delivering drug solutions

ABSTRACT

In one aspect, a pen needle assembly is provided herein which includes a hub, and a needle fixed to the hub, the needle having proximal and distal ends with a lumen extending therebetween. The needle extends distally from the hub to define an exposed length between the distal end of the needle and the hub in the range of about 5.0 to 9.0 mm. The hub defines a post formed about the needle, the post having a distally-facing first skin engaging surface. The exposed length of the needle extends distally from the first skin engaging surface. The hub also defines a distally-facing second skin engaging surface which at least partially circumscribes the first skin engaging surface. The second skin engaging surface being located proximally of the first skin engaging surface. Advantageously, a pen needle assembly is provided having two skin engaging surfaces which provide stability in achieving subcutaneous injections.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.14/172,288, filed Feb. 4, 2014, which is a division of U.S. patentapplication Ser. No. 13/138,549, filed Dec. 13, 2011, which is based onPCT Patent Application No. PCT/US2010/026129, filed Mar. 3, 2010, whichis based on and claims priority of U.S. Provisional Patent ApplicationSer. No. 61/209,050, filed Mar. 3, 2009, the entire disclosure of saidprior applications being incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to pen needle assemblies and, more particularly,to pen needle assemblies for delivering drug suspensions.

BACKGROUND OF THE INVENTION

Pen needle assemblies are well known in the art. To minimize discomfort,pen needle assemblies typically use needles in the range of 29 to 31gauge. Where a pen injector is used to mix or reconstitute substancesinto a solution for delivery, thin needles, such as those in the rangeof 29 to 31 gauge, may be susceptible to clogging by agglomerationswhich result from re-suspension or incomplete mixing of the substances.

SUMMARY OF THE INVENTION

In one aspect, a pen needle assembly is provided herein which includes ahub, and a needle fixed to the hub, the needle having proximal anddistal ends with a lumen extending therebetween. The needle extendsdistally from the hub to define an exposed length between the distal endof the needle and the hub in the range of about 5.0 to 9.0 mm. The hubdefines a post formed about the needle, the post having adistally-facing first skin engaging surface. The exposed length of theneedle extends distally from the first skin engaging surface. The hubalso defines a distally-facing second skin engaging surface which atleast partially circumscribes the first skin engaging surface. Thesecond skin engaging surface being located proximally of the first skinengaging surface. Advantageously, a pen needle assembly is providedhaving two skin engaging surfaces which provide stability in achievingsubcutaneous injections.

Objects, advantages, and salient features of the invention will becomeapparent from the following detailed description, which, taken inconjunction with the annexed drawings, discloses exemplary embodimentsof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above benefits and other advantages of the various embodiments ofthe present invention will be more apparent from the following detaileddescription of exemplary embodiments of the present invention and fromthe accompanying figures, in which:

FIG. 1 is an exploded view showing a pen needle assembly formed inaccordance with the subject invention along with usable packaging;

FIG. 2 is a cross-sectional schematic showing an injection formed with apen needle assembly formed in accordance with the subject invention;

FIGS. 3 and 4 show different configurations of a second skin engagingsurface usable with a pen needle assembly in accordance with the subjectinvention;

FIG. 5 is a chart showing test results;

FIG. 6 is a cross-section showing a pen needle assembly formed inaccordance with the subject invention in a packaged state; and

FIG. 7 is an enlarged view taken from section 7 of FIG. 6.

Throughout the drawings, like reference numbers will be understood torefer to like parts, components and structures.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

With reference to the drawing figures, a pen needle assembly is shownand generally designated with the reference numeral 10. The pen needleassembly 10 is useable with various pen injectors for administeringmedicament. The pen needle assembly 10 is particularly well-suited toadminister medicament which is mixed into a solution inside theassociated pen injector, such as by re-constitution or mixing of two ormore components (wet or dry), such as liquid and solid powder ofparticles, and/or medicament having particles in the formulationsuspension. In either case, particles or particle agglomerations may befound in the medicament which may partially or wholly clog the lumen ofa prior art administering needle. The pen needle assembly 10 provides anarrangement for delivering the suspension through minimizing theclogging of a needle lumen.

The pen needle assembly 10 generally includes a hub 12 and a needle 14.The needle 14 is fixed to the hub 12 by any known technique, e.g.,adhesion, and includes a proximal end 16, a distal end 18 and a lumen 20extending therebetween.

As used herein, the term “proximal”, and derivatives thereof, shallrefer to a direction away from a patient during use (i.e., thenon-patient end), and the term “distal”, and derivatives thereof, shallrefer to a direction towards a patient during use (i.e., the patientend).

The hub 12 includes a body 22 which is preferably formed of a polymericmaterial, e.g. thermoplastic. The body 22 includes an open proximal end24 which exposes the proximal end 16 of the needle 14. Preferably, thepen needle assembly 10 is removably mountable onto a medical peninjector 1. This permits replacement of the pen needle assembly inallowing multiple injections to be administered by the pen injector 1.To this end, mounting features 26 are formed on the body 22 for engagingcooperating mounting features F on the pen injector 1. The mountingfeatures 26 and F may be of any known type including cooperatingthreads, mechanical features (e.g., bayonet-type lock) and/or surfaceconfigurations, such as Luer surfaces. Alternatively, the hub 12 may benon-removably fixed to, or formed integrally with, the pen injector 1.This configuration is useable with a single-use injector which isdisposed of after one injection.

The proximal end 16 of the needle 14 is sized to access medicament Mcontained within the pen injector 1 with the hub 12 being mounted to thepen injector 1. Typically, the medicament M will be housed within areservoir or cartridge accommodated within the pen injector with aseptum S forming a seal at the distal end thereof. The proximal end 16is sufficiently sized to pierce through the septum S to access themedicament M with the hub 12 being mounted to the pen injector 1. Themedicament M may have clumps or agglomerations A floating therein.

The pen needle assembly 10 is configured to administer an injection ofthe medicament M into the subcutaneous region of a patient's skin. Inaddition, the pen needle assembly 10 is configured to minimize cloggingin the lumen 20 resulting from insufficient depth of injection (i.e.,clogging caused by attempted injection into the dermis/epidermis layer).With the pen needle assembly 10, an injection may be administered in thesubcutaneous region with minimal concern for clogging of the lumen 20.

The needle 14 has an exposed length L1 which is defined between thedistal end 18 of the needle 14 and the hub 12. The exposed length L1 isthe portion of the needle 14 that extends distally from the hub 12 andthat may be inserted into the patient during an injection. The exposedlength L1 is in the range of about 5.0 to 9.0 mm.

In addition, a beveled surface 28 extends proximally from the distal end18 of the needle 14 in which distal opening 30 is defined. The lumen 20terminates at the distal opening 30. As will be appreciated by thoseskilled in the art, the beveled surface 28 may include variousconfigurations including having multiple facets or bevels with thesurfaces being of various configurations, including being partially orwholly planar and/or arcuate. The beveled surface 28 provides the distalend 18 of the needle 14 with a sharpened configuration for insertioninto a patient.

Length L2 of the needle 14 corresponds to the length of needle 14 overwhich the beveled surface 28 extends. The length L2 is preferably in therange of 30%-60% of the exposed length L1. The length L2 is measuredalong the longitudinal axis of the needle 14 and not along the length ofthe beveled surface 28. The length L2, being in the range of 30%-60% ofthe exposed length L1, provides the distal opening 30 with an elongatedshape that is minimally susceptible to clogging in the lumen 20 by anyof the agglomerations A formed in the medicament M. It is additionallypreferred that the needle 14 be of 25 gauge or larger in size, morepreferably in the range of 20-25 gauge. With the needle 14 being of 25gauge or larger in size, the lumen 20 is larger in cross-sectional sizethan a lumen of typical prior art pen needles (typical prior art penneedles being in the range of 29-31 gauge). With the needle 14 being ofa larger gauge (25 gauge or larger in size), the lumen 20 is betterconfigured to deliver the medicament M as a suspension (e.g.,reconstituted or mixed solution) in being less susceptible to cloggingof the lumen 20 by any of the agglomerations A formed in the medicamentM.

In addition, to achieve a subcutaneous injection, it is preferred thatthe body 22 of the hub 12 define a post 32 about the needle 14. The post32 includes a distally-facing first skin engaging surface 34, which isdefined about the needle 14 continuously or discontinuously. The firstskin engaging surface 34 acts as a stop against excessive insertion ofthe needle 14 into the patient. Preferably, the exposed length L1 isdefined between the distal end 18 of the needle 14 and the first skinengaging surface 34. It is preferred that the post 32 be limited in itsouter diameter so as to be smaller than the overall diameter orfootprint of the body 22. Preferably, the first skin engaging surface 34radiates outwardly from the needle 14 and terminates at an outerdiameter D1, which more preferably is 0.121″.

It is further preferred that the hub 12 defines a distally-facing secondskin engaging surface 36 which is spaced radially outwardly from, and atleast partially circumscribes, the first skin engaging surface 34. Thesecond skin engaging surface 36 is located proximally of the first skinengaging surface 34 so as to define an offset δ which is preferably inthe range of 0.07″-0.10″. As shown in FIG. 2, the first skin engagingsurface 34 provides a focused point of contact against a patient's skin,which results in some deflection thereof. The second skin engagingsurface 36 is spaced radially outwardly and rearwardly, by the offset δ,to provide a second hard stop against excessive insertion of the needle14 into a patient's skin. The second skin engaging surface 36 providesstability to the pen needle assembly 10 during injection. Due to thelimited diameter of the first skin engaging surface 34, there may belimited engagement with a patient's skin with insufficient stability forthe injection. The second skin engaging surface 36 adds stability.

With reference to FIGS. 3 and 4, the second skin engaging surface 36 maybe defined by various configurations which are continuous ordiscontinuous. With reference to FIG. 3, the second skin engagingsurface 36 is defined with an annular shape at the end of wall 38 whichcompletely circumscribes the post 32. The second skin engaging surface36 preferably defines a diameter D2 of 0.340″. In the embodiment of FIG.3, the diameter D2 coincides with the inner edge of the second skinengaging surface 36. With reference to FIG. 4, the second skin engagingsurface 36 may defined over a series of fins 40 which radiate outwardlyfrom the post 32. Spaces 42 are located between the fins 40. The fins 40are shaped and positioned so that collectively the second skin engagingsurface 36 may be defined thereby which limits insertion of the needle14 into the patient's skin, particularly to achieve a subcutaneousinjection. With the embodiment of FIG. 4, the fins 40 may terminateradially outwardly at the diameter D2 so that the diameter D2 coincideswith the outer edge of the second skin engaging surface 36. In anyregard, it is preferred that the diameter D2 be defined along a freeedge of the second skin engaging surface 36 where, adjacent thereto,skin may be deflected or deformed. With the embodiment of FIG. 3, thediameter D2 coincides with an inner free edge of the second skinengaging surface 36, while in the embodiment of FIG. 4, the diameter D2coincides with an outer free edge of the second skin engaging surface36.

As shown in FIG. 2, the pen needle assembly 10 is intended forinjections administered generally perpendicularly to a patient's skin.

Preferably, the ratio of the diameter D1 to the diameter D2 (D1/D2ratio) is in the range of 0.25 to 0.58, more preferably the ratio is0.36. It has been found that with these ratios, acceptable skin tensionis created at the site of the injection with good stability. It has beenfound that if the diameter D2 is too large, insufficient skin tension iscreated and a shallow injection may result; if the diameter D2 is toosmall, there may be a lack of stability for injection, with lessperpendicularity (which is desired) and a shallow injection resulting.

With reference to FIG. 5, testing was conducted to evaluate theperformance of subcutaneous injections with the pen needle assembly 10.The testing was conducted on a swine animal model, and it is believedthat similar or same results will be achieved in injections on humans.The left hand column of FIG. 5 represents test results from using thepen needle assembly 10 as shown in FIG. 2, with the post 32 defining thefirst skin engaging surface 34 and the second skin engaging surface 36being proximally set back by the offset δ. More specifically, the needle14 used for this test was of a 23 gauge type with the offset δ being0.09″, the diameter D1 being 0.121″, the exposed length L1 being 7 mm,and the length L2 being 3 mm. In addition, the second skin engagingsurface 36 had its inner edge coincide with the diameter D2 being0.340″.

With respect to the results, the injections were observed and ranked: aranking of 4 corresponds to a deep subcutaneous injection; a ranking of3 corresponds to a subcutaneous injection; a ranking of 2 corresponds toa shallow subcutaneous injection; a ranking of 1 corresponds to anintradermal injection; and, a ranking of 0 corresponds to a needleclogged by the dermis/epidermis. As can be seen in the left column, withthe pen needle assembly 10 of the subject invention, repeatedsubcutaneous injections were achieved without clogging.

In particular, with reference to FIG. 5, using the pen needle assembly10 of the subject invention, two shallow subcutaneous injections wereachieved; fourteen subcutaneous injections were achieved; and, four deepsubcutaneous injections were achieved. No clogging or intradermalinjections were experienced.

The right band column of FIG. 5 represents a pen needle assembly whichhad the same parameters as discussed above with respect to the first setof test results but was without the offset δ between the first andsecond skin engaging surfaces 34, 36 (i.e., the first and second skinengaging surfaces 34, 36 are coplanar). As can be seen, the majority ofthe injections were of the shallow subcutaneous type with a number ofclogged needles also being achieved. In particular, three cloggedneedles were experienced; two intradermal injections were achieved;eleven shallow subcutaneous injections were achieved; and, foursubcutaneous injections were achieved. The clogged needles resulted fromexcessively shallow needle insertion with failed injection into thedermis/epidermis; the needles were sufficiently clogged by thedermis/epidermis to not perform an injection.

As can be seen in FIG. 5, with the pen needle assembly 10 of the subjectinvention, repeated subcutaneous injections without clogging by thedermis/epidermis may be achieved. Subcutaneous injections as referred toherein are differentiated from shallow subcutaneous injections and deepsubcutaneous injections. A subcutaneous injection is administered in acentral area of the subcutaneous layer. It is desired to achieveinsertion at this depth, rather than in a shallow or deep subcutaneousregion where injections therein may coincide with the dermis/epidermisor muscle regions, respectively, of the patient. With the pen needleassembly 10 of the subject invention, medicament, which may be insuspension or prone to agglomeration, may be repeatedly delivered intothe subcutaneous region with low susceptibility to clogging.

The pen needle assembly 10 may be packaged for use, as shown in FIGS. 1,6 and 7. In particular, a rigid shell 44 may be provided sized toaccommodate the pen needle assembly 10 therein with at least a portionof the needle 14, preferably at least the distal end 18 of the needle14, being covered. Preferably, the shell 44 has a cup-shaped body 46with an open proximal end 48 and an interior 49 into which the penneedle assembly 10 may be seated. To prevent excessive insertion of thepen needle assembly 10 into the body 46 during packaging, shoulder 50may define a reduced-diameter region in the interior 49 which limits theextent of insertion of the pen needle assembly 10 into the body 46. Asshown in FIG. 6, it is preferred that minimal clearance be definedbetween the shoulder 50 and the second skin engaging surface 36 to limitpassage thereby of contaminants. Sterility of the exposed length L1 ofthe needle 14 may be better maintained in this manner. It is preferredthat the proximal end 24 of the body 22 be exposed when seated in thebody 46 such that the pen injector 1 may be mounted to the pen needleassembly 10 with it being contained within the shell 44. It is alsopreferred that the distal end 52 of the shell 44 be spaced from thedistal end 18 of the needle 14 with the pen needle assembly 10 beingseated within the body 46. In this manner, blunting of the needle 14 andinadvertent piercing of the shell 44 by the needle 14 may be avoided.

The shell 44 may be maintained on the pen needle assembly 10 in anyknown manner which permits releasable retainment of the shell 44 on thehub 12, including by frictional interengagement, frangible connection,mechanical connection and/or fusion or adhesion, such as spot fusion oradhesion. The force of retention for maintaining the shell 44 in the hub12 should be great enough to prevent separation of the shell 44 from thehub 12 during normal transporting and storage, which may involve jarringor other force application to the combined package. It is preferred thatthe shell 44 be re-mountable onto the hub 12 after use (i.e., after aninjection) to cover the needle 14 in a post-use state. It is preferredthat the configuration for releasable retainment permit re-mounting ofthe shell 44 and retention thereof on the hub 12. In this manner, thepen needle assembly 10 may be disposed of with the needle 14 in a usedstate being covered.

Preferably, as shown in FIG. 3, one or more resilient snaps 54 may beprovided on the hub 12 which are received in snap engagement incorresponding snap recesses 56 formed on the shell 44, as shown in FIGS.6 and 7. In a packaged state, as shown in FIGS. 6 and 7, the inherentresilience of the interengagement of the snaps 54 and the snap recesses56 provide sufficient retaining force for holding the shell 44 onto thehub 12. The inherent resilience, however, is surmountable to permitdisengagement of the snaps 54 from the snap recesses 56 in allowingseparation of the shell 44 from the hub 12 to permit use. The shell 44may be re-mounted onto the hub 12 after use with the snaps 54 and thesnap recesses 56 being caused to re-engage. As will be appreciated bythose skilled in the art, the snaps 54 and the snap recesses 56 may beformed on the hub 12/and or the shell 44.

It is preferred that an audible signal be generated upon the shell 44being properly mounted onto the hub 12 in entering the retained statetherewith. For example, the snaps 54 may have sufficient inherentresilience so as to generate a click, or other audible signal, upon snapengaging the snap recesses 56.

The pen needle assembly 10 is preferably mounted onto the pen injector 1prior to any necessary preparation of the medicament M, such as bymixing or reconstituting components found in the pen injector 1. It ispreferred that a sufficiently strong retaining force be provided for theshell 44 on the hub 12 so as to retain the shell 44 on the hub 12 duringany shaking or other agitation of the pen injector 1 in preparing themedicament M. The agitation may include tapping the shield 44 against asurface. The retaining force needs to be sufficiently strong to preventseparation under such conditions. Subsequent manual removal of theshield 44 from the hub 12, however, must be permitted to allow primingof the needle 14 and subsequent injection.

The inherent resilience of the retaining force may also be sufficientlystrong to permit rotational force applied to the shell 44 to betransmitted to the hub 12 in mounting the pen needle assembly 10 ontothe pen injector 1, particularly where the mounting features 26 and Fare cooperating threads.

A barrier sheet or film 58 may be also provided to be applied inremovable securement across the proximal end 48 of the shell 44 towholly enclose, with the shell 44, the pen needle assembly 10 in apackaged state. Preferably, the sheet 58 provides a sterility barrier.The pen needle assembly 10 may be sterilized prior to packaging withinthe shell 44 or while inside the shell 44. The sheet 58 may be securedto the shell 44 using known techniques, such as adhesion or fusion. Agrip 60 may be provided to extend from the sheet 58 to facilitateremoval thereof.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the scope of the present invention. Thedescription of exemplary embodiments of the present invention isintended to be illustrative, and not to limit the scope of the presentinvention. Various modifications, alternatives and variations will beapparent to those of ordinary skill in the art, and are intended to fallwithin the scope of the invention as defined in the appended claims andtheir equivalents.

What is claimed is:
 1. A pen needle assembly comprising: a hub having aproximal end and a distal end with an axial face; a collar extendingaxially from said axial face of said hub and spaced radially inward froma peripheral edge of said body, said collar having an axially facing endwall; a post extending from said end wall, said post having a distal endand a central opening extending through said post and receiving a needlefixed to said post, said needle extending axially from said post, saiddistal end of said post having an annular axial face spaced radiallyoutward from said needle and defining a first annular skin contactsurface; a member having an annular shape and extending axially fromsaid distal end of said collar, said member spaced radially outward fromsaid post and having an annular axial face spaced axially from saidaxial face of said post, and where said axial face of said post isspaced distally from said axial face of said member a distance of atleast about 0.07.
 2. The pen needle assembly according to claim 1,wherein said needle extends distally from said hub to define an exposedlength in the range of about 5.0 to 9.0 mm, and where said axial face ofsaid post is spaced distally from said axial face of said member adistance of about 0.07 to about 0.10 inch.
 3. The pen needle assemblyaccording to claim 1, wherein said annular axial face of said post has afirst diameter D1 and said annular axial surface of said annular memberhas a second diameter D2, and where a ratio of said diameter D1 to saiddiameter D2 is about 0.25:1 to about 0.58:1.
 4. The pen needle assemblyaccording to claim 3, wherein said ratio of said first diameter D1 tosaid second diameter D2 is about 0.36:1.
 5. The pen needle assemblyaccording to claim 1, wherein said annular axial face of said post isspaced from said annular axial face of said annular member a distance ofabout 0.07 to 0.10 inch.
 6. The pen needle assembly according to claim5, wherein said axial face of said post is radially spaced from saidannular face of said member a distance of about 0.09 inch.
 7. The penneedle assembly according to claim 1, wherein said annular member isradially spaced from said post a distance to form an annular recessbetween said post and said annular member.
 8. The pen needle assemblyaccording to claim 1, further comprising a shell configured forreleasable retainment on said hub, said shell being retainable on saidhub with said shell covering at least a portion of said needle, theforce of said retainment being sufficiently great to maintain said shellretained on said hub with said pen needle assembly being mounted to amedical pen injector with the medical pen injector being shaken toprepare a medicament contained therein for administration to a patient.9. The pen needle assembly according to claim 8, wherein said releasableretainment is obtained by one or more of the group consisting offrictional interengagement, frangible connection, mechanical connection,fusion and adhesion.
 10. A pen needle assembly comprising: a hub havinga proximal end and a distal end with an axial face; a post extendingaxially from said distal end of said hub, said post having a distal endand a central opening extending through said post and receiving aneedle, where said needle is fixed to said post and extends axially fromsaid post, said distal end of said post having an annular axial facespaced radially outward from said needle and defining a first annularskin contact surface; and a member extending axially from said distalend of said body, said member having an outer peripheral edge spacedradially outward from said post and having an axially facing distalsurface spaced axially from said annular axial face of said post, andwhere said annular axial face of said post is spaced axially from saiddistal surface of said annular member a distance of about 0.07 to about0.10 inch.
 11. The pen needle assembly according to claim 10, whereinsaid hub further comprises a body having a collar extending axially fromsaid distal end of said body and spaced radially inward from aperipheral edge of said body, said collar having an end wall, and wheresaid post and said member extend from said end wall.
 12. The pen needleassembly according to claim 11, wherein said member comprises aplurality of fins extending radially outward from said post, said finshaving an axially facing surface spaced proximally from said distal endof said post.
 13. The pen needle assembly according to claim 12, whereineach of said fins has a radial end face oriented substantially parallelto a longitudinal axis of said hub.
 14. The pen needle assemblyaccording to claim 11, wherein said distal end of said post has asubstantially conical shaped portion.
 15. The pen needle assemblyaccording to claim 11, wherein said member has an annular axial facespaced axially from said annular axial face of said post.
 16. The penneedle assembly according to claim 11, wherein said needle extendsdistally from said hub to define an exposed length in the range of about5.0 to 9.0 mm.
 17. The pen needle assembly according to claim 15,wherein said annular axial face of said post has a first diameter D1 andsaid annular axial face of said member has a second diameter D2, andwhere a ratio of said diameter D1 to said diameter D2 is about 0.25:1 toabout 0.58:1.
 18. The pen needle assembly according to claim 16, saidratio of said first diameter D to said second diameter D2 is about0.36:1.
 19. The pen needle assembly according to claim 15, wherein saidannular axial face of said post is spaced from said annular axial faceof said annular member a distance of about 0.07 to 0.10 inch.
 20. Thepen needle assembly according to claim 19, wherein said axial face ofsaid post is radially spaced from said annular surface of said annularmember a distance of about 0.09 inch.
 21. The pen needle assemblyaccording to claim 19, wherein said axial face of said post is radiallyspaced from said annular surface of said annular member a distance ofabout 0.09 inch.
 22. A method of injecting a medicament to a patient,comprising the steps of: connecting a pen needle assembly to a medicalpen injector containing the medicament, said pen needle assemblycomprising; a hub having a proximal end and a distal end with an axialface; a collar extending from said axially from said axial face of saidhub and spaced radially inward from a peripheral edge of said body, saidcollar having an axially facing end wall; a post extending from said endwall, said post having a distal end and a central opening extendingthrough said post and receiving a needle fixed to said post andextending axially from said post, said distal end of said post having anannular axial face spaced radially outward from said needle and defininga first annular skin contact surface; an annular member extendingaxially from said distal end of said collar, said annular shaped memberspaced radially outward from said post and having an annular axial facespaced axially from said axial face of said post, and where said axialface of said post is spaced distally from said axial face of saidannular member a distance of about 0.07 to about 0.10 inch; introducingsaid needle into the patient where said annular axial face of said postand said annular axial face of said annular member contact a surface ofthe skin of the patient to limit a depth of penetration; and injectingthe medication into the patient.
 23. The method according to claim 22,wherein said needle extends distally from said hub to define an exposedlength in the range of about 5.0 to 9.0 mm.
 24. The method according toclaim 23, wherein said annular axial face of said post has a firstdiameter D1 and said annular axial surface of said annular member has asecond diameter D2, and where a ratio of said diameter D1 to saiddiameter D2 is about 0.25:1 to about 0.58:1.
 25. The method according toclaim 24, wherein said annular axial face of said post is spaced fromsaid annular axial face of said annular member a distance of about 0.07to 0.10 inch.
 26. The method according to claim 25, said annular memberis radially spaced from said post a distance to form an annular recessbetween said post and said annular member.